Process for the production of spongy metal

Abstract

A plant for producing sponge metal, in particular sponge iron, from charging materials consisting of metal ore or iron ore respectively, preferably in lumps and/or pellets, and optionally fluxes, comprising at least one first gas source ( 1, 3 ) dispensing a CO— and H 2 - containing feedgas, a CO 2 elimination plant ( 17, 17′ ) and optionally a heating means ( 22, 25 ) for the feedgas from the first gas source ( 1, 3 ) is provided with a reduction reaction ( 20 ) which forms a further gas source for a CO— and H 2 -containing feedgas and serves for receiving metal ore, a reducing-gas feed duct ( 19 ) leading to this reduction reactor ( 20 ) and an export-gas discharge duct ( 31 ) from said further reduction reactor ( 20 ), wherein a conveying duct ( 30 ) for at least a portion of the export gas formed in the reduction reactor ( 20 ) and serving as a feedgas is flow-connected with the reducing-gas feed duct ( 19 ) of the reduction reactor ( 20 ) via a CO 2 elimination plant and optionally a heating means. To increase economic efficiency, the plant is characterized in that at least two CO 2 elimination plants ( 17, 29, 17′, 29′ ) are provided which are adapted to be connectable in parallel and at least one of which is connectable with the conveying duct ( 30 ) for the export gas that is produced in the reduction reactor ( 20 ) forming the further gas source and that is conducted as a recycle gas, and at least one CO 2 elimination plant ( 17, 17′ ) for the feedgas from the first gas source is provided and each of the CO 2 elimination plants is flow-connectable with the reduction reactor ( 20 ) forming the further gas source (FIG. 1 ).

What is claimed is:  
     
       1. Method for producing sponge metal from charging materials comprising metal ore and optionally fluxes wherein a CO 2 , CO—, H 2 - and tar containing feedgas from a first gas source comprising a melt-down gasifying zone ( 8 ) and a first reduction zone ( 12 ) is subjected to CO 2  elimination and optionally to heating and an at least largely CO 2 -free reducing gas is supplied to at least one further reduction zone ( 21 ) forming a further CO 2 , CO, nitrogen and tar containing gas source, to serve for the direct reduction of metal ore and which after reaction with the ore is withdrawn as an export gas and said export gas at least partially is also subjected to CO 2  elimination as a recycle gas for the reduction zone ( 21 ), characterized in that both the feedgas from the first gas source ( 8 ,  12 ) and the recycle gas recycled from the reduction zone ( 21 ) are each subjected to CO 2  elimination separately. 
     
     
       2. Method according to claim  1 , characterized in that the feedgas from said first gas source is generated by directly reducing iron ore to sponge iron in a first reduction zone ( 12 ) to produce liquid pig iron or liquid steel pre-products from iron ore, the sponge iron is melted in a melt-down gasifying zone ( 8 ) under the supply of carbon carriers and oxygen-containing gas and a CO 2 , CO— H 2  and tar-containing reducing gas is produced which is introduced into the first reduction zone ( 12 ), is reacted there and withdrawn as the export gas that forms the feedgas. 
     
     
       3. Method according to claim  1 , characterized in that CO 2  elimination of the recycle gas is effected by the pressure-swing adsorption method. 
     
     
       4. Method according to claim  2 , characterized in that a portion of the reducing gas from the melt-down gasifying zone ( 8 ) is subjected to tar extraction and subsequently is admixed with the export gas of the first reduction zone ( 12 ) and the recycle gas from the further reduction zone ( 21 ) is subjected to CO 2  elimination with its tar content unchanged. 
     
     
       5. Method according to claim  1 , characterized in that the recycle gas from the further reduction zone ( 21 ) is divided into two partial streams and one partial stream is subjected to CO 2  elimination separately and the other partial stream is admixed to the feedgas or export gas respectively from the first gas source or first reduction zone ( 12 ) respectively before the latter undergoes CO 2  elimination and is subjected to a separate CO 2  elimination together with the same. 
     
     
       6. Method according to claim  1 , characterized in that the feedgas or export gas respectively from the first gas source or first reduction zone ( 12 ) respectively is divided into two partial streams and one partial stream is admixed to the recycle gas from the second reduction zone ( 21 ), preferably at least to a partial stream of the same, and that each partial stream is subjected to CO 2  elimination independently of the partial stream that has been branched off. 
     
     
       7. Method according to claim  5 , characterized in that each of the partial streams of the export gas or recycle gas respectively, optionally after mixture with a partial stream of the recycle gas or export gas respectively, is compressed separately before CO 2  elimination is effected. 
     
     
       8. Method according to claim  1 , characterized in that the reducing gas supplied to the further reduction zone ( 21 ) also contains nitrogen and in case of an increased nitrogen content of said reducing gas, the gas pressure of said reducing gas is increased. 
     
     
       9. Method according to claim  1 , wherein the sponge metal is sponge iron and the metal ore is iron ore. 
     
     
       10. Method according to claim  1 , wherein the metal ore is in the form of lumps or pellets. 
     
     
       11. Method according to claim  2 , characterized in that CO 2  elimination for the feedgas or export gas respectively from the first gas source or the first reduction zone ( 12 ) respectively is effected while maximizing the reductant content, and CO 2  elimination for the recycle gas from the further reduction zone ( 21 ) is effected optionally with a reduction in the reductants contained in said recycle gas and with minimizing the nitrogen content of the recycle gas.